1. Field of the Invention
The present invention relates to a damper, and more particularly to a damper for a pivot door. The damper has a piston movably received inside the damper and having a first channel and a second channel respectively and selectively communicating with a space full of hydraulic oil, such that the movement of the piston is able to be slowed by the interchange of the communication of the first channel and the space and the second channel and the space.
2. Description of Related Art
Normally, a damper is mounted on a door, especially a glass door, to prevent the glass door from damage caused by a sudden movement. A conventional damper has a drive shaft securely inserted into a housing for connecting with the door and a cam mounted on the drive shaft. When the door is open/closed, the cam is driven by the drive shaft and a spring mounted around the drive shaft is compressed. The compressed spring is able to provide resistance to the door to prevent the door from a sudden movement, such that the glass door is protected.
However, the geometric shape of the damper has to be big and the configuration of the damper is complicated, such that the cost of the damper is high.
To overcome the shortcomings, the present invention tends to provide an improved damper to mitigate and obviate the aforementioned problems.
The primary objective of the invention is to provide an improved damper that has a space full of hydraulic oil, which functions to provide a resistance to a motion, and a piston movably received in the housing of the damper and provided with a first channel and a second channel. The first and second channel are individually and selectively in communication with the space for different phases of the movement of the piston, such that the movement of the piston is able to be slowed and the movement of the door is thus slowed.
Another objective of the invention is to provide a dust-free cap for the drive shaft. The dust-free cap has continuous serration formed on an inner face of the cap, such that when the cap is mounted onto the drive shaft, the continuous serration provides multiple barrels to prevent aliens from entering the inner structure of the damper.
With such an arrangement, the combination of the piston, a piston rod centrally connected to the piston and a T-shaped mount that is securely mounted on a guide board, the alignment of the movement of the piston inside the housing is enhanced and so as the smoothness of the movement of the piston. Furthermore, the life span of the damper is greatly increased.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.